Heat exchanger

ABSTRACT

A HEAT EXCHANGER COMPRISING A SHELL, SURROUNDING A CORE-UNIT CONSISTING OF PARALLEL TUBES SUPPORTED BY AXIALLY SPACED HEADERS. ONE HEADER IS FIXED AXIALLY, WHILE THE OTHER HEADER IS FREE OT SHIFT AXIALLY IN THE SHELL IN RESPONSE TO TEMPERATURE FLUCTUATIONS. THE BONNET CLOSING ONE END OF THE SHELL IS PROVIDED WITH A DIAMETRICALLY-POSITIONED RESILIENT SEALING MEMBER WHICH ENGAGES THE SURFACE OF THE AXIALLY-FREE HEADER TO PROVIDE A PAIR OF CHAMBERS IN THE BONNET, AND TO PREVENT FLUID FROM PASSING FROM ONE CHAMBER TO THE OTHER. MEANS IS ALSO PROVIDED TO INDICATE INSTANCES OF LEAKAGE BETWEEN THE MUTUAL PERIPHERIES OF THE SHELL AND THE AXIALLY-FREE HEADER.

R. MYERS HEAT EXCHANGER ZSheets-Sheet 1 Filed Jan. 13.- 1869 R. MYERS HEAT EXCHANGER ZSheets-Sheet 2 Filed Jan. 1:, I 1969 B I 0 6 g e my N A k P 4 .1, I. v! 5 \QW l NM. NM, Mn QM United States Patent Office 3,572,429 HEAT EXCHANGER Royse Myers, 4118 Hounds Trail, Racine, Wis. 53402 Filed Jan. 13, 1969, Ser. No. 790,669 Int. Cl. F28f 9/00 US. Cl. 165-82 1 Claim ABSTRACT OF THE DISCLOSURE A heat exchanger comprising a shell, surrounding a core-unit consisting of parallel tubes supported by axiallyspaced headers. One header is fixed axially, while the other header is free to shift axially in the shell in response to temperature fluctuations. The bonnet closing one end of the shell is provided with a diametrically-positioned resilient sealing member which engages the surface of the axially-free header to provide a pair of chambers in the bonnet, and to prevent fluid from passing from one chamber to the other. Means is also provided to indicate instances of leakage between the mutual peripheries of the shell and the axially-free header.

BACKGROUND OF THE INVENTION (1) Field of the invention This invention concerns heat exchangers in which one fluid absorbs heat from another fluid by conduction.

(2) Description of the prior art Prior art devices of the type concerned, generally omit a provision to compensate for axial expansion between the tube unit or bundle, and the shell: An example of the prior art being the patent to Young No. 3,111,167.

SUMMARY This invention comprises a heat exchanger comprising a tubular shell closed at each end by bonnets. A plurality of tubes extend axially and within the shell, and are secured integrally to a header at each end of the shell. Fluid to be cooled is permitted to circulate around the tubes from one end of the shell to the other. Heat absorbing fluid is caused to flow through the tubes to absorb heat from the fluid flowing around them. Axiallypositioned batfles direct the fluid to be cooled, across the bundle of tubes in order to more efficiently accomplish the heat transfer.

An object of this invention is to provide axial freedom for one of the headers in order to permit unrestricted axial expansion of the tube unit or bundle with respect to the shell.

Another object is to provide a resilient seal to engage the surface of the axially-free header during the period of axial expansion and contraction so as to establish separate chambers in the bonnet forming the end of the exchanger.

Another object is to provide a drain aperture in the periphery of the shell so as to detect leaks between the mutual peripheries of the shell and the axially-free header.

Further objects and advantages of this invention will become apparent from a consideration of the following detailed description taken in connection with the accompanying drawings wherein an embodiment of the invention is shown. It is, however, to be understood that the invention is not limited to the details disclosed, but includes all such variations as fall within the spirit of the invention.

Referring to the drawings:

FIG. 1 is an elevational view of a four-pass heat exchanger embracing the invention.

FIG. 2 is an end view thereof.

3,572,429 Patented Mar. 23, 1971 FIG. 3 is an end view taken in the direction of 3-3 of FIG. 1.

FIG. 4 is an enlarged view of a portion of FIG. 2.

FIG. 5 is a section taken at 55 of FIG. 4.

FIG. 6 is a section taken at 6-6 of FIG. 2.

FIG. 7 is a section taken at 7-7 of FIG. 6.

FIG. 8 is an enlarged fragmentary view taken at 8-8 of FIG. 7.

FIG. 9 is a fragmentary view taken at 9'9 of FIG. 6.

FIG. 10 is an enlarged fragmentary section taken at 1010 of FIG. 8.

The heat exchanger shown in FIG. 1 comprises a shell generally designated as 8, and which consists of a tubular member 10, usually of steel, and which is fitted into recesses in hubs 12 and 14. Welds such as 16 secure the tubular member and the hubs 12 and 14 into an integral unit designated as 8, which has a uniform cylindrical bore therethrough. Conduits 18 and 20 provide inlet and outlet passageways for admission of the fluid to be cooled.

The tube unit or bundle 22, as shown in FIG. 6, is inserted in the shell 8 and comprises tubes 24, grouped as shown, and usually of brass. A first header 26 of brass or similar material, is provided with apertures to receive the tubes 24 and which are positioned against axial displacement by means of silver soldering to the header 26.

A second header 28 is positioned at the other end of shell 8 and comprises a brass or copper-coated steel cupped member having a peripheral chamfer and slidable within the bore of shell 8 which bore extends through hubs 12 and 14. Tubes 24 are also silver-soldered in apertures in the wall of header 28, thus making the tube unit an integral one. Batfles 29, 31 and 33, usually of brass, are axially positioned on the tube bundle and are secured integrally therewith against axial displacement, by any suitable means. The function of baffles 29, 31 and 33 is to compel the fluid being cooled, to cross and recross the tubes 24, thereby obtaining an efficient cooling cycle.

End bonnet 30 has a chamber 32 to permit circulation of the cooling fluid, and is provided with openings 34 and 36 to receive inlet and outlet connections to admit the fluid for passage through the tubes 24. A plug 38 is provided which has affixed therein an anode of zinc 40 which functions to retard corrosion of the elements of the exchanger when corrosive elements are present in the cooling fluid.

When the exchanger is being assembled, the tube unit 22 is inserted into the shell 8 to the position shown in FIG. 6, with an asbestos neoprene gasket or the like intermediate the end face of hub 12 and the header 26. Another gasket 48 is placed between header 26 and bonnet 30. Cap screws 50 and suitable lock washers secure the header 26, gaskets 46 and 48 and bonnet 30 to hub 12.

A bonnet 52 provides the means of closing the end of hub 14 and requires two chambers 54 and 56, inasmuch as this device is a four-pass heat exchanger. In view of the axial movement of the header 28 caused by expansion and contraction, it is necessary to provide a resilient sealing member of suitable material such as 58, in order to maintain a separation of the chambers 54 and 56. This sealing member will be under constant compression at all times.

Sealing member 58 is of the shape shown, having a lip 60 at the diametrically-positioned ends as shown in FIGS. 6 and 8. Lip 60 conforms to the contours of the edge of the header 28 and the bore of hub 14, thus assuring a seal against the flow of fluid between chambers 54 and 56 during axial movement of header 28.

Sealing member 58 is supported on header 28 in a grooved member 62 which is silver-soldered or otherwise secured to the header, as shown in FIGS. 8, 9 and 10. Additional support is provided for sealing member 58 by means of a Wall 64, cast integrally with bonnet 52. A slot 66 is provided in wall 64 to provide lateral support for the sealing member. When bonnet 52 is being assembled to hub 14, a gasket of suitable material 68, is placed between the hub 14 and the bonnet 52, and cap screws 70 with suitable lockwashers complete the assembly.

In order to avoid failure in maintaining separation of the fluid circulation about the tubes and that circulating within the tubes, a pair of rings 42 and 44 are provided in the periphery of the bore of the hub 14. These rings are of the type well known, and need not be further described. Rings 42 and 44 are spaced axially as shown. A drain hole or aperture 72 is provided in hub 14 intermediate the 0 rings 42 and 44, as shown in FIGS. 4 and 5. This provision will detect leaks in either axial direction, and would indicate a need for the replacement of the 0 rings.

When it is necessary to remove the tube unit or bundle 22 for servicing or cleaning, it is only necessary to remove the bonnet 30 and the gasket 48. Header 26 can then be grasped and the entire tube unit withdrawn. If the 0 rings 42 and 44 require replacing, bonnet 52 can also be removed so as to provide convenient access to the rings.

It will be apparent that this novel heat exchanger permits convenient access to the interior of the unit for the purpose of servicing or cleaning, and the axially-free header prevents distortion of the tubes and headers during extreme temperature variatios.

The above being a complete description of an illustrative embodiment of the invention, what is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A heat exchanger, comprising a cylindrical shell having an axis, and first and second axially-spaced ends, a tube bundle extending axially within said shell and comprising a plurality of tubes, a first header integral with one extremity of said tubes and fixed axially adjacent said first end, a second header having a cylindrical portion and axially free within said shell and integral with the other extremity of said tubes, said second header having an end surface normal to said axis and positioned adjacent said second end, the intersection of said cylindrical portion and said end surface defining a peripheral chamfer, and a bonnet secured to said second end having a chamber substantially diametrically-co-extensive with the bore of said shell, said bonnet having an axially-directed wall in said chamber and common to the axis of said shell and extending axially to define a plurality of chambers, said wall terminating adjacent said end surface, a diamerticallyextending resilient seal lying in the plane of said Wall and positioned intermediate said wall and said end surface to define a plurality of fluid-separating chambers in said bonnet, the diametrically-opposed ends of said seal terminating in lips substantially conforming to the contour of said shell, said chamfer and said end surface and means to confine said seal against displacement relative to said end surface and in a direction normal to said axis.

References Cited UNITED STATES PATENTS 2,009,877 7/1935 Dodd 165158X 2,191,179 2/1940 ODonnell l158X 2,292,524 8/1942 Jacocbs -82 3,151,674 10/1964 Heller et a1 165158 FOREIGN PATENTS 399,690 10/1933 Great Britain 165-458 414,906 8/1934 Great Britain 165--158 ALBERT W. DAVIS, JR., Primary Examiner US. Cl. X.R. 

